The present invention generally relates to vibrating machines; it more particularly relates to a system for reducing dynamic loads exerted on the bearings that support the vibrating shaft assembly of a vibrating machine. Vibrating equipment in which the invention might be employed include vibrating screens, compactors, vibrating feeders, conveyors, shakers, and the like.
Vibration machinery commonly employ rotating unbalanced shafts to generate vibrations that can be harnessed for a desired objective such as impelling aggregate material along a vibrating platform or separating aggregate through a vibrating screen. The unbalanced mass associated with the shaft, because it has a center of gravity that is different than the shaft's axis of rotation, produces a centrifugal force that generates useful vibrations as the shaft rotates. The degree of vibration produced will depend on the weight of the unbalanced mass, the distance that the mass center of gravity is offset from the shaft's rotational axis, and the angular velocity of the shaft.
As a result of the centrifugal force produced by the unbalanced shaft of a vibrating machine, the dynamic load on the bearings supporting the shaft will be increased as compared to a balanced shaft where no vibrational forces are produced. The bearings supporting a rotating unbalanced shaft will therefore experience greater stress, and this will in turn reduce bearing life and increase maintenance costs for a given size of bearing.
Heretofore, the problem of bearing life in a vibrating shaft assembly has been approached by selecting bearings that are large enough to withstand the extreme bearing loads involved. However, large bearings are relatively expensive and are limited in their speed range.
The present invention overcomes the problem of bearing loads in vibrating shaft assemblies by providing a means for counteracting the radial centrifugal forces transmitted to the shaft's support bearings. Indeed, it is contemplated that the invention will reduce bearing loads to the minimum allowed by bearing manufactures. The invention also provides a means for axially centering the shaft within the vibrating unit additionally reducing any associated axial bearing loads. The invention will permit the use of smaller bearings for a given vibrating shaft size and will reduce the substantial maintenance costs and down time associated with bearing replacement.